1. Field of the Invention
This invention relates in general to communication devices having an oscillator, and more specifically to a communication device having channel based oscillator aging compensation.
2. Description of the Related Art
Communication devices, such as cellular telephones, pagers, and fixed station transceivers are widely used today. All such communications devices share one common problem, over time drift of the oscillator which controls channel frequency, can lead to unintelligible communications, and in the extreme, complete failure to receive information being transmitted over a radio frequency channel. This problem is especially problematic for communication devices used in unattended locations that are used to provide remote monitoring of operating equipment or to provide security for a facility. As a result, such communication devices have to be periodically checked by a trained serviceman, and the oscillator retuned, should the oscillator have drifted off frequency. The problem can be alleviated to some extent through the used of high stability oscillators, which would extended the time interval between which checking the oscillator is performed, but such oscillators are often costly, and do not necessarily justify the added expense to the communication device.
What is needed is a method and apparatus by which communication devices having relatively low stability oscillators can be regularly adjusted without the intervention of the user of the device.